How can architecture express abstract theological beliefs in concrete form?

Santa Costanza, Rome

The Church in the Fourth Century

Christianity existed for centuries before its first houses of public worship were built. It was not until Emperor Constantine’s Edict of Milan (313AD) that the Roman Empire permanently established toleration for the church. By that time, the church had already been developing its traditions, culture, theology and worship for generations.

Official establishment also meant a change in the church’s social profile. The membership of the early church was weighted toward those who were willing to risk persecution, or who were lower on the social scale, with less to lose by converting. But in the fourth century, church membership became a viable option for more wealthy and powerful people.

During this period, the visual representation of Christ evolved. In earlier times, when Christians were buried in the catacombs underground, there Jesus was commonly shown as a youthful Good Shepherd (for example in the catacombs of Priscilla or Callixtus). Later, as Christianity became more identified with the Roman Empire, Christ was shown enthroned as a lawgiver (on sarcophagi and mosaics), eventually developing a halo, beard, long hair and purple robe. Rather than Christ’s crucifixion and death, artists emphasized his life and teachings.

The Ten Commandments’ prohibition on graven images, combined with the prominence of cult statues in Greco-Roman pagan temples, meant that freestanding Christian sculpture was almost unknown. Only sarcophagi displayed carved Christian sculpture as part of their program.

The First Church Buildings: Basilicas and Central Plans

The Emperor Constantine was the first patron of Christian architecture, and he supported it with building on a massive scale, for example in Bethlehem, Jerusalem and his new imperial capital, Constantinople. In Rome itself, the new fourth-century church buildings showed both an ability to adapt existing architectural ideas to new purposes, and also distinctive contrasts with the older pagan forms of worship.

Anyone who observed the construction of Old Saint Peter’s, begun in 319 on the site of Peter’s grave, would have been struck by the fact that this new house of worship was designed as a basilica and not as a temple. Up to this point, a basilica was simply an assembly hall meant to hold large crowds, not for any religious purpose (e.g. the Basilica Ulpia or the Aula Palatina). In contrast, pagan temples were quite small, holding only the shrines for cult veneration; public ceremonies took place outdoors.

The new Christian churches had no cult statues to venerate; the buildings existed to gather the faithful together inside for worship. And, while pagan temples had exterior decoration addressed to crowds outside, the Christian basilica had a plain brick exterior. Thus, the very form of the new building indicated a major difference between pagan worship and Christian worship. Additionally, St. Peter’s large scale suggests the size of the crowds now attracted to the church under Constantine.

While the longitudinally-oriented basilica would become the dominant form for churches in the West, the central plan (circular or polygonal) would be used for churches in the East, as well as for smaller auxiliary structures in the West. Western basilica churches might have centrally-planned chapels, baptisteries or mausoleums adjacent or attached to them. In Rome, as we will see, the large basilica of Saint Agnes was adjacent to the much smaller, central-plan mausoleum of Constantina, which is now the church of Santa Costanza.

Central plans were long familiar in antiquity, and often associated with memorials for the dead, from the Tholos of Delphi (380-370BC) to the Pantheon in Rome (126AD), to the mausoleum built in Spalato (now Split, Croatia), by Emperor Diocletian, author of the last great Roman persecution of Christians, before his retirement in 305AD. Santa Costanza shows how the central plan could be turned to a distinctively Christian purpose, while drawing on aspects of this pre-Christian heritage.

The Patrons

Among the very earliest surviving Christian buildings is the church now known as Santa Costanza, originally the Mausoleum of Constantina…

The Site

From the earliest days of the church, Christians had buried their dead in catacombs, rock-cut underground tunnels outside the city walls of Rome. As the new church buildings went up on the locations of martyrs’ graves, they too were concentrated outside the old walls. Santa Costanza, for example, is located on a former suburban estate belonging to the imperial family, on the Via Nomentana heading northeast out of the city.